Reducing Degrees of Freedom in Surgical Suturing: Implications for Minimally Invasive Device Development-A Prospective Experimental Study.

Open surgery allows the use of all 6 degrees of freedom (DOF; x-y-z and roll-pitch-yaw), whereas laparoscopy requires working under limitation to 4 axes. We present a prospective experimental study evaluating translational and rotational DOF restriction in surgical suturing tasks. An experimental platform included a kinematic structure that limited the maneuverability of the surgical instruments. The subjects (n=20) worked in a randomized order using (1) 6DOF, (2) 4DOF with 3 translational and 1 rotational DOF (4TRANS), and (3) 4DOF with 1 translational and 3 rotational DOF (4ROT). The time required to perform each task was recorded. Suturing and knot tying were significantly faster under 6DOF compared with 4ROT (both P<0.001) and 4TRANS (both P<0.001). Assessment of subjective difficulty and impairment showed most favorable results for 6DOF. The advantage of rotational compared with translational DOF should be considered in the development of future surgical devices.

Learning curves, potential and speed in training of laparoscopic skills: a randomised comparative study in a box trainer.

BACKGROUND: The effectiveness of practical surgical training is characterised by an inherent learning curve. Decisive are individual initial starting capabilities, learning speed, ideal learning plateaus, and resulting learning potentials. The quantification of learning curves requires reproducible tasks with varied levels of difficulty. The hypothesis of this study is that the use of three-dimensional (3D) vision is more advantageous than two-dimensional vision (2D) for the learning curve in laparoscopic training. METHODS: Forty laparoscopy novices were recruited and randomised to a 2D Group and a 3D Group. A laparoscopy box trainer with two standardised tasks was used for training of surgical tasks. Task 1 was a positioning task, while Task 2 called for laparoscopic knotting as a more complex process. Each task was repeated at least ten times. Performance time and the number of predefined errors were recorded. 2D performance after 3D training was assessed in an additional final 2D cycle undertaken by the 3D Group. RESULTS: The calculated learning plateaus of both performance times and errors were lower for 3D. Independent of the vision mode the learning curves were smoother (exponential decay) and efficiency was learned faster than precision. The learning potentials varied widely depending on the corresponding initial values and learning plateaus. The final 2D performance time of the 3D-trained group was not significantly better than that of the 2D Group. The final 2D error numbers were similar for all groups. CONCLUSIONS: Stereoscopic vision can speed up laparoscopic training. The 3D learning curves resulted in better precision and efficiency. The 3D-trained group did not show inferior performance in the final 2D cycle. Consequently, we encourage the training of surgical competences like suturing and knotting under 3D vision, even if it is not available in clinical routine.

How Much Stereoscopic Effect Does Laparoscopy Need? Controlled, Prospective Randomized Trial on Surgical Task Efficiency in Standardized Phantom Tasks.

BACKGROUND: To regain 2-eyed vision in laparoscopy, dual-channeled optics have been introduced. With this optics design, the distance between the 2 front lenses defines how much stereoscopic effect is seen. This study quantifies the impact of an enhanced and a reduced stereo effect on surgical task efficiency. METHODS: A prospective single-blinded study was performed with 20 laparoscopic novices in an inanimate experimental setting. A standard bichannelled stereo system was used to perform a suturing and knotting task. The working distance and the task size were scaled to vary the stereo effect and, thereby, simulate hypothetic stereo optics with enhanced and reduced optical bases. The task performances were timed, and the number of trials for stitching out was counted. The participants finally filled out a questionnaire to collect subjective impressions. RESULTS: The increase of the stereo effect by 50% caused no objective improvement in laparoscopic knotting compared with typical 3D (control group with stereo basis of 4.5 mm). But ergonomic disadvantages (headache) were subjectively reported in 1 of 20 cases in the questionnaire. The reduction of the stereo effect by one-third led to a significantly longer average execution time. There was no significant dependence found between stereo effect and number of stich-out trials, stitching precision, or knotting quality. CONCLUSIONS: Considering laparoscopy, it does not seem advisable to enhance the stereo effect because of ergonomic problems. Otherwise, a miniaturization of the 3D scope (5 mm version) is problematic because its benefit mostly shrinks with the reduced stereo effect.

Evaluation of self-educational training methods to learn laparoscopic skills - a randomized controlled trial.

BACKGROUND: Evaluation of two different self-educational methods (video assisted learning versus video assisted learning plus a nodal point operation primer) on learning laparoscopic suturing and intracorporal knotting. METHODS: Randomized controlled trial at the laparoscopic surgical training center, University of Tubingen with 45 surgical novices first year medical students being pretested for dexterity. After self-educational training for 90 min with either method (Group A: video assisted learning, Group B: video assisted learning plus a nodal point operation primer) participants had to perform five laparoscopic intracorporal knots. Assessed were number of knots completed (maximum of five knots counted, knot integrity, technical proficiency and knotting time per knot. Primary outcome measure is a composed knot score combining knot integrity, technical proficiency and knotting time. RESULTS: Group B (n = 23) achieved a significantly higher composed knot score than Group A (n = 22) (53.3 ± 8.4 versus 46.5 ± 13.6 points respectively, p = 0.016). Median knotting time per completed knot was significantly different between Group B and Group A (308 s [100-1221] versus 394 s [138-1397] respectively, p = 0.001). Concerning number of completed knots there was a trend towards more knots achieved in Group B (4.2 ± 1.2 versus 3.55 ± 1.4 respectively, p = 0.075) . CONCLUSIONS: The use of a nodal point operation primer highlighting essential key steps of a procedure augment the success of learning laparoscopic skills as suturing and intracorporal knotting. (UIN researchregistry3866, March 22, 2018).

For 3D laparoscopy: a step toward advanced surgical navigation: how to get maximum benefit from 3D vision.

The authors are grateful for the interesting perspectives given by Buchs and colleagues in their letter to the editor entitled "3D Laparoscopy: A Step Toward Advanced Surgical Navigation." Shutter-based 3D video systems failed to become established in the operating room in the late 1990s. To strengthen the starting conditions of the new 3D technology using better monitors and high definition, the authors give suggestions for its practical use in the clinical routine. But first they list the characteristics of single-channeled and bichanneled 3D laparoscopes and describe stereoscopic terms such as "comfort zone," "stereoscopic window," and "near-point distance." The authors believe it would be helpful to have the 3D pioneers assemble and share their experiences with these suggestions. Although this letter discusses "laparoscopy," it would also be interesting to collect experiences from other surgical disciplines, especially when one is considering whether to opt for bi- or single-channeled optics.

Utility of routine ultrasound after laparoscopic cholecystectomy to detect early postoperative complication.

BACKGROUND AND AIM: In up to 3% of laparoscopic cholecystectomies, procedure-related complications occur. Routine postoperative ultrasound is one means of screening for these complications. The aim of this study was to determine the utility of this practice after laparoscopic cholecystectomy. METHODS: A series of consecutive patients (n = 1,044) undergoing laparoscopic cholecystectomy from January 2007 to January 2011 was analysed. Primary endpoint was the detection of procedure-related complications by routine ultrasound. RESULTS: Routine ultrasound within the first 48 h after laparoscopic cholecystectomy was performed in 967 of 1,044 patients. Overall, 25 (2.4%) of the 1,044 patients suffered from procedure-related complications, but only in 2 patients was the complication detected by routine ultrasound. Findings were false-positive in 103 patients. This corresponds to a sensitivity of 8% and a specificity of 89%. Hospital stay was prolonged in the false-positive group. CONCLUSION: Routine postoperative ultrasound has a low sensitivity for the detection of complications after laparoscopic cholecystectomy. In almost all cases, the diagnosis is initiated by clinical findings. Therefore, routine ultrasound is of limited value in screening for postoperative complications after cholecystectomy.

3D HD versus 2D HD: surgical task efficiency in standardised phantom tasks.

BACKGROUND: Common video systems for laparoscopy provide the surgeon a two-dimensional image (2D), where information on spatial depth can be derived only from secondary spatial depth cues and experience. Although the advantage of stereoscopy for surgical task efficiency has been clearly shown, several attempts to introduce three-dimensional (3D) video systems into clinical routine have failed. The aim of this study is to evaluate users' performances in standardised surgical phantom model tasks using 3D HD visualisation compared with 2D HD regarding precision and working speed. METHODS: This comparative study uses a 3D HD video system consisting of a dual-channel laparoscope, a stereoscopic camera, a camera controller with two separate outputs and a wavelength multiplex stereoscopic monitor. Each of 20 medical students and 10 laparoscopically experienced surgeons (more than 100 laparoscopic cholecystectomies each) pre-selected in a stereo vision test were asked to perform one task to familiarise themselves with the system and subsequently a set of five standardised tasks encountered in typical surgical procedures. The tasks were performed under either 3D or 2D conditions at random choice and subsequently repeated under the other vision condition. Predefined errors were counted, and time needed was measured. RESULTS: In four of the five tasks the study participants made fewer mistakes in 3D than in 2D vision. In four of the tasks they needed significantly more time in the 2D mode. Both the student group and the surgeon group showed similarly improved performance, while the surgeon group additionally saved more time on difficult tasks. CONCLUSIONS: This study shows that 3D HD using a state-of-the-art 3D monitor permits superior task efficiency, even as compared with the latest 2D HD video systems.

Transanal endoscopic microsurgery-based transanal access for colorectal surgery: experience on human cadavers.

Transanal endoscopic microsurgery (TEM) was described in 1983 for local excision of rectal tumors. In the context of natural orifice translumenal endoscopic surgery, we have modified the original TEM system and developed a new set of instruments. These are more curved and, in addition, steerable. After extensive studies in an ex-vivo model, we developed a novel technique for transanal rectosigmoid resection and colorectal anastomosis. The technique comprises closure of the rectal lumen by purse-string suture, transection of the rectal wall distal to the closure, circumferential mobilization of rectum and mesorectal tissue in the anatomical plane from below upward, control of the inferior mesenteric vessel, removal of mobilized colorectum through the anus, and, finally, the colorectal anastomosis by either stapled or hand-sutured technique. This procedure was performed on three alcohol-glycerol preserved well-built human cadavers (M:F=2:1). The average operating time was 190 minutes. The average length of the resected specimen was 23 cm. There was no fecal contamination or injury to the resected specimen. Postprocedure laparotomy revealed adequate mesorectal resection and no inadvertent injury to other viscera. During dissection in the pelvis, as the resected rectum was pushed upward, an unobstructed "empty pelvis" situation was developed in the operating site, thus facilitating the mesorectal resection. Transanal access for colorectal surgery seems feasible. It provides a precise definition of the distal safety margin, good view of the pelvis for meticulous mesorectal resection, and reduces the abdominal wall trauma. These may enhance the outcome of colorectal resection. However, further clinical studies can only substantiate these findings.

A novel single-port technique for transanal rectosigmoid resection and colorectal anastomosis on an ex vivo experimental model.

BACKGROUND: In the context of natural orifice translumenal endoscopic surgery (NOTES), we developed a new set of rigid instruments according to the principles of transanal endoscopic microsurgery (TEM).These instruments are long, curved, and steerable by rotating two wheels near its handle. Our success in transvaginal cholecystectomy in human with these instruments motivated us to explore the feasibility of rectosigmoid resection through the anus. METHODS: The young bovine large bowel with attached organs is collected en bloc and reintegrated into an anatomically designed trainer to reproduce the human anatomy. The technique comprises the following: (1) closure of the rectal lumen by an endolumenal pursestring suture; (2) transection of the rectal wall 1 cm distal to the pursestring suture and continuation of the dissection toward the fascia and upward excising the mesorectal tissue; (3) inferior mesenteric artery is divided near its origin; (4) the colon is mobilized up to the splenic flexure; (5) the mobilized colon is brought down to the pelvis, ligated twice at the intended proximal resection site, and divided between the ligatures; (6) specimen is delivered transanally; and (7) intestinal continuity is restored by stapled or hand-sutured anastomosis. RESULTS: Twelve rectosigmoid resections, 20 stapled, and 27 hand-sutured anastomoses were performed in two experimental setups. Mean operation time for the resection part was 78.6 min (standard deviation (SD)=9.9). The average specimen length was 37.2 cm. During dissection in the pelvis, as the specimen was pushed upward and toward abdomen, an "empty pelvis" view of the working field was achieved, facilitating dissection. The mean operation time for hand-sutured and stapled anastomoses were 47.7 (SD=6.9) and 43.3 (SD=7.1) min, respectively. Both groups had one anastomotic leak. CONCLUSIONS: Transanal rectosigmoid resection is feasible with TEM technology. The unobstructed "empty pelvis" view is likely to enhance the quality of mesorectal dissection.